1. Field of the Invention
The present invention relates to a power supply unit and a lighting device for a vehicle.
2. Description of the Related Art
In a related art, a lighting device for a vehicle uses a light emitting diode element (for example, refer to JP-A-2002-231013). When the light emitting diode element is lit, a forward voltage is generated at both ends of the light emitting diode element according to a predetermined threshold voltage.
The forward voltage generated in the light emitting diode element greatly fluctuates for each individual body. Therefore, in the lighting device for the vehicle, in order to cope with the fluctuation of the forward voltage, the light emitting diode element is lit by controlling an electric current. However, from the viewpoint of designing a luminous intensity distribution, in some cases, the lighting device for the vehicle uses a plurality of light emitting diode elements, which are connected in parallel with each other. In this case, when an electric current supplied to each row of the light emitting diode elements, which are connected in parallel with each other, is set by an individual circuit, the circuit scale is increased. Further, the manufacturing cost of the lighting device for the vehicle is increased.